Yes, you have done your best by working and building your story; well done!
Now what's the next thing?
The next thing is to start writing your screenplay.
One thing you should bear in mind is that a screenplay has some
elements. These elements make up a template upon which your story should
be fixed.
The elements are scene heading, action, character name, dialogue and others.

So as you transform your story to a screenplay, you should take some certain steps.

(1) Try to visualize the story. Make it a live-story in your mind

(2) Write it as if you are watching it happen

(3) Every scene has a location. So right in your mind, you have to imagine
and create locations for the scenes; and then try to keep them
consistent.
This point is important because two or more scenes can be in one
location. Imagining and keeping this location consistent will help you
know the space it has, the directions an action can go, movements the
characters can make, and how you can make your descriptions.
With this, any time you want to write a scene in the location, you already know what it looks like.

(4) You have to sometimes go the extra mile of rehearsing the actions you plan to write yourself.
Some actions can be easily performed by the real actors, why some other
actions are not. You must try and write what an actor can act.

(5) Say the dialogues you plan to write. Hear how they sound. Check how interactive they are.
Your siblings or friends can also help you. You and they will rehearse it.

(6) You have to again imagine certain names your characters will bear.
Gone are the times when script writers arbitrarily assign names to their characters.
There are 'sweet names' that beautify your screenplay. These names are
the names your audience will always remember fast whenever they are
telling your screenplay or the movie from your screenplay.